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I am using a opto triac rated at 100C operational. It controls an externa SCR in a very common fashion. The opto Is physically located next to a heat source component making the opto temperature rise reach just a little past its operational temperature when tested in a chamber.

In looking around for a higher rated part I noticed that all OPTO TRIACs are rated either for 85C or 100C but nothing above that. The junction temperature is rated at 125C.

Is there a limitation in opto triac design that a higher rated temperature device is not available? Or do I just have to search harder

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High temperatures will cause the LED and probably the clear insulating material inside to deteriorate relatively quickly. You probably won't find components rated far above 100 degrees C.

Digikey lists some Isocom units as 110 degrees C, didn't check if the datasheet agrees (you should).

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  • \$\begingroup\$ I looked at the Isocom but as company it looks very disorganized from a online presence perspective. I was not able to get their datasheet and what I found did not have the temperature rating. I run some testing and only some of the ICs when heated to 120C would shut off but overall they would normally take upto 130-140C before shutting off. Of course the outliers will get you, if you do not think to measure their temperature and they are located inclose proximity of a heatsink. \$\endgroup\$ – DIODEX Dec 22 '17 at 15:47
  • \$\begingroup\$ Personally I think you should avoid running them anywhere near that hot or you may have problems with reliability over time. \$\endgroup\$ – Spehro Pefhany Dec 22 '17 at 16:11

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